Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients

J Infect. 2020 Aug;81(2):e39-e45. doi: 10.1016/j.jinf.2020.05.077. Epub 2020 Jun 3.


Objectives: SARS-CoV-2 antibody assays are needed for serological surveys and as a complement to molecular tests to confirm COVID-19. However, the kinetics of the humoral response against SARS-CoV-2 remains poorly described and relies on the performance of the different serological tests.

Methods: In this study, we evaluated the performance of six CE-marked point-of-care tests (POC) and three ELISA assays for the diagnosis of COVID-19 by exploring seroconversions in hospitalized patients who tested positive for SARS-CoV-2 RNA.

Results: Both the ELISA and POC tests were able to detect SARS-CoV-2 antibodies in at least half of the samples collected seven days or more after the onset of symptoms. After 15 days, the rate of detection rose to over 80% but without reaching 100%, irrespective of the test used. More than 90% of the samples collected after 15 days tested positive using the iSIA and Accu-Tell® POC tests and the ID.Vet IgG ELISA assay. Seroconversion was observed 5 to 12 days after the onset of symptoms. Three assays suffer from a specificity below 90% (EUROIMMUN IgG and IgA, UNscience, Zhuhai Livzon).

Conclusions: The second week of COVID-19 seems to be the best period for assessing the sensitivity of commercial serological assays. To achieve an early diagnosis of COVID-19 based on antibody detection, a dual challenge must be met: the immunodiagnostic window period must be shortened and an optimal specificity must be conserved.

Keywords: COVID-19; ELISA; SARS-CoV-2 antibodies; point of care tests.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Viral / blood*
  • Betacoronavirus / immunology
  • COVID-19
  • COVID-19 Testing
  • Clinical Laboratory Techniques*
  • Coronavirus Infections / diagnosis*
  • Coronavirus Infections / immunology
  • Enzyme-Linked Immunosorbent Assay*
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / diagnosis*
  • Pneumonia, Viral / immunology
  • Point-of-Care Systems*
  • Reagent Kits, Diagnostic
  • SARS-CoV-2
  • Sensitivity and Specificity
  • Seroconversion*
  • Serologic Tests
  • Young Adult


  • Antibodies, Viral
  • Reagent Kits, Diagnostic